use std::io::ErrorKind;
use std::{cmp, vec};

use crate::config::Config;
use crate::file_kind::FileKind;
use crate::multipart;
use crate::multipart::UploadConfig;
use actix_multipart::Multipart;
use actix_web::{error, web, Error, HttpResponse};
use async_std::{
    channel::Sender,
    fs::{self, OpenOptions},
    path::PathBuf,
};
use chrono::Duration;
use rand::prelude::SliceRandom;
use sqlx::postgres::PgPool;

const INDEX_HTML: &str = include_str!("../template/index.html");
const AUTH_HIDE_JS: &str = include_str!("../template/auth-hide.js");
const UPLOAD_HTML: &str = include_str!("../template/upload.html");
const AUTH_SNIPPET_HTML: &str = include_str!("../snippet/auth.html.snippet");
const MAX_SIZE_SNIPPET_HTML: &str = include_str!("../snippet/max_size.html.snippet");

const ID_CHARS: &[char] = &[
    'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'j', 'k', 'm', 'n', 'p', 'q', 'r', 's', 't', 'u', 'v',
    'w', 'x', 'y', 'z', '1', '2', '3', '4', '5', '6', '7', '8', '9',
];

pub async fn index(
    req: web::HttpRequest,
    config: web::Data<Config>,
) -> Result<HttpResponse, Error> {
    let filled_index_html = fill_index_html(req, config);
    Ok(HttpResponse::Ok()
        .content_type("text/html")
        .body(filled_index_html))
}

fn fill_index_html(req: web::HttpRequest, config: web::Data<Config>) -> String {
    let upload_url = format!("{}/upload", get_host_url(&req));
    let auth_snippet = config
        .no_auth_limits
        .as_ref()
        .map_or("", |_| AUTH_SNIPPET_HTML);
    let max_size_snippet = config
        .max_file_size
        .as_ref()
        .map_or("", |_| MAX_SIZE_SNIPPET_HTML);
    INDEX_HTML
        .replace("{max_size_snippet}", max_size_snippet)
        .replace(
            "{max_size}",
            &render_file_size(config.max_file_size.unwrap_or(0)),
        )
        .replace("{auth_snippet}", auth_snippet)
        .replace(
            "{auth_time}",
            &config
                .no_auth_limits
                .as_ref()
                .map(|limit| limit.max_time)
                .map_or("".into(), render_duration),
        )
        .replace(
            "{auth_large_time}",
            &config
                .no_auth_limits
                .as_ref()
                .map(|limit| limit.large_file_max_time)
                .map_or("".into(), render_duration),
        )
        .replace(
            "{auth_large_size}",
            &config
                .no_auth_limits
                .as_ref()
                .map(|limit| limit.large_file_size)
                .map_or("".into(), render_file_size),
        )
        .replace("{upload_url}", upload_url.as_str())
}

fn render_file_size(size: u64) -> String {
    let magnitude = cmp::min((size as f64).log(1024.0) as u32, 5);
    let prefix = ["", "ki", "Mi", "Gi", "Ti", "Pi"][magnitude as usize];
    let value = size / (1024_u64.pow(magnitude));
    format!("{}{}B", value, prefix)
}

fn render_duration(duration: Duration) -> String {
    let days = duration.num_days();
    let hours = duration.num_hours() % 24;
    let minutes = duration.num_minutes() % 60;
    let seconds = duration.num_seconds() % 60;
    let mut elements = vec![];
    if let Some(name) = pluralize(days, "tag", "e") {
        elements.push(name);
    }
    if let Some(name) = pluralize(hours, "stunde", "n") {
        elements.push(name);
    }
    if let Some(name) = pluralize(minutes, "minute", "n") {
        elements.push(name);
    }
    if let Some(name) = pluralize(seconds, "sekunde", "n") {
        elements.push(name);
    }
    elements.join("+")
}

fn pluralize(number: i64, word: &str, suffix: &str) -> Option<String> {
    match number {
        0 => None,
        1 => Some(format!("{} {}", number, word)),
        _ => Some(format!("{} {}{}", number, word, suffix)),
    }
}

pub async fn auth_hide(config: web::Data<Config>) -> Result<HttpResponse, Error> {
    if let Some(no_auth_limits) = &config.no_auth_limits {
        let auth_hide_js = AUTH_HIDE_JS
            .replace(
                "{no_auth_max_time}",
                &no_auth_limits.max_time.num_seconds().to_string(),
            )
            .replace(
                "{no_auth_large_file_max_time}",
                &no_auth_limits.large_file_max_time.num_seconds().to_string(),
            )
            .replace(
                "{no_auth_large_file_size}",
                &no_auth_limits.large_file_size.to_string(),
            );
        Ok(HttpResponse::Ok()
            .content_type("application/javascript")
            .body(auth_hide_js))
    } else {
        Err(error::ErrorNotFound("file not found"))
    }
}

pub async fn upload(
    req: web::HttpRequest,
    payload: Multipart,
    db: web::Data<PgPool>,
    expiry_watch_sender: web::Data<Sender<()>>,
    config: web::Data<Config>,
) -> Result<HttpResponse, Error> {
    let (file_id, file_name) = create_unique_file(&config).await.map_err(|file_err| {
        log::error!("could not create file {:?}", file_err);
        error::ErrorInternalServerError("could not create file")
    })?;

    let parsed_multipart = multipart::parse_multipart(payload, &file_id, &file_name, &config).await;
    let UploadConfig {
        original_name,
        valid_till,
        kind,
        delete_on_download,
    } = match parsed_multipart {
        Ok(data) => data,
        Err(err) => {
            if file_name.exists().await {
                fs::remove_file(file_name).await.map_err(|file_err| {
                    log::error!("could not remove file {:?}", file_err);
                    error::ErrorInternalServerError(
                        "could not parse multipart; could not remove file",
                    )
                })?;
            }
            return Err(err);
        }
    };

    let db_insert = sqlx::query(
        "INSERT INTO Files (file_id, file_name, valid_till, kind, delete_on_download) \
        VALUES ($1, $2, $3, $4, $5)",
    )
    .bind(&file_id)
    .bind(&original_name)
    .bind(valid_till.naive_local())
    .bind(kind.to_string())
    .bind(delete_on_download)
    .execute(db.as_ref())
    .await;
    if let Err(db_err) = db_insert {
        log::error!("could not insert into datebase {:?}", db_err);
        fs::remove_file(file_name).await.map_err(|file_err| {
            log::error!("could not remove file {:?}", file_err);
            error::ErrorInternalServerError(
                "could not insert file into database; could not remove file",
            )
        })?;
        return Err(error::ErrorInternalServerError(
            "could not insert file into database",
        ));
    }

    log::info!(
        "{} create new file {} (valid_till: {}, kind: {}, delete_on_download: {})",
        req.connection_info().realip_remote_addr().unwrap_or("-"),
        file_id,
        valid_till,
        kind,
        delete_on_download
    );

    expiry_watch_sender.send(()).await.unwrap();

    let redirect = if kind == FileKind::Binary {
        let encoded_name = urlencoding::encode(&original_name);
        format!("/upload/{}/{}", file_id, encoded_name)
    } else {
        format!("/upload/{}", file_id)
    };

    let url = get_file_url(&req, &file_id, Some(&original_name));
    Ok(HttpResponse::SeeOther()
        .header("location", redirect)
        .body(format!("{}\n", url)))
}

async fn create_unique_file(
    config: &web::Data<Config>,
) -> Result<(String, PathBuf), std::io::Error> {
    loop {
        let file_id = gen_file_id();
        let mut file_name = config.files_dir.clone();
        file_name.push(&file_id);
        match OpenOptions::new()
            .write(true)
            .create_new(true)
            .open(&file_name)
            .await
        {
            Ok(_) => return Ok((file_id, file_name)),
            Err(error) if error.kind() == ErrorKind::AlreadyExists => continue,
            Err(error) => return Err(error),
        }
    }
}

fn gen_file_id() -> String {
    let mut rng = rand::thread_rng();
    let mut id = String::with_capacity(5);
    for _ in 0..5 {
        id.push(*ID_CHARS.choose(&mut rng).expect("ID_CHARS is not empty"));
    }
    id
}

fn get_host_url(req: &web::HttpRequest) -> String {
    let conn = req.connection_info();
    format!("{}://{}", conn.scheme(), conn.host())
}

fn get_file_url(req: &web::HttpRequest, id: &str, name: Option<&str>) -> String {
    if let Some(name) = name {
        let encoded_name = urlencoding::encode(name);
        format!("{}/{}/{}", get_host_url(req), id, encoded_name)
    } else {
        format!("{}/{}", get_host_url(req), id)
    }
}

pub async fn uploaded(req: web::HttpRequest) -> Result<HttpResponse, Error> {
    let id = req.match_info().query("id");
    let name = req.match_info().get("name");
    let url = get_file_url(&req, id, name);
    let upload_html = UPLOAD_HTML.replace("{url}", url.as_str());
    Ok(HttpResponse::Ok()
        .content_type("text/html")
        .body(upload_html))
}